Watch Live: Sally Yates, James Clapper Testify Before Senate on Russia

Sally Yates testifies during a Senate Judiciary Committee hearing in Washington July 8, 2015. Kevin Lamarque/File Photo/Reuters

Updated | Two Obama administration officials will appear before a Senate Committee on the Judiciary subcommittee on Monday to testify about Russian influence in the 2016 presidential election. The testimony of one of those officials, former Acting Attorney General Sally Yates, has been widely anticipated, with even President Donald Trump weighing in early on Monday.

Yates was appointed as deputy attorney general under Loretta Lynch by former President Barack Obama, and then served as acting attorney general in the earliest days of the Trump administration. On Monday, she will provide her most public comments since the Trump administration dismissed her in January—within days of his inauguration—after she refused to order Department of Justice lawyers to defend his executive order that halted travel from certain countries and suspended the refugee program. In a statement announcing the dismissal, the White House said she had "betrayed the Department of Justice" and called her "weak on borders and very weak on illegal immigration."

Related: How the FBI's Russia investigation could work

Her dismissal came days after she reportedly alerted White House Counsel Don McGahn about concerns she had over Trump's national security adviser at the time, Michael Flynn, regarding his conversations with Sergey Kislyak, the Russian ambassador to the United States.

A separate congressional body that is investigating Russia's election tampering—the House Permanent Select Committee on Intelligence—had invited Yates to testify in March. The committee then canceled the scheduled hearing, allegedly because the White House was concerned about what she might say about Flynn. The White House has denied this.

On Monday, Yates will face questioning by Senator Lindsey Graham, chairman of the Senate Judiciary's Subcommittee on Crime and Terrorism, that will likely focus on her knowledge of Flynn's conversations with the Russian ambassador and her warnings on the subject, which officials allegedly ignored until Flynn's forced resignation in February. During testimony before the Senate Judiciary Committee last Wednesday, FBI Director James Comey said Yates had also come to him with concerns about Flynn.

Obama also issued a warning about Flynn, telling Trump during their November 10 meeting not to hire him, NBC News and CNN reported on Monday, hours before the start of the Senate hearing.

People on the left are looking forward to hearing from the former acting attorney general, who they consider a hero for refusing to defend Trump's executive order in January. On Sunday, supporters tweeted using the hashtag #SallyYatesIsAPatriot.

But Trump and others on the right seem more concerned with leaks than Russian interference and possible collusion with Trump associates. On Monday, the president tweeted, likely referring to McGahn, "Ask Sally Yates, under oath, if she knows how classified information got into the newspapers soon after she explained it to W.H. Council."

Former Director of National Intelligence James Clapper is also testifying before the judiciary subcommittee on Monday. He will likely face questioning related to what the U.S. intelligence community knew about Russia's election tampering, and when they knew about it. He will likely pass on the more sensitive questions, because the hearing is open, and refer to the declassified report that intelligence agencies published in January. The report concluded that Russian President Vladimir Putin ordered up a campaign "to undermine public faith in the U.S. democratic process, denigrate Secretary [Hillary] Clinton, and harm her electability and potential presidency," and that he and his government "developed a clear preference for" Trump. Clapper has said publicly that Russia accomplished what it set out to do, calling the effort a "huge success."

Graham could also bring up claims that the FBI wiretapped Trump Tower, and how the FBI conducted surveillance on Carter Page, a foreign policy adviser to the Trump campaign. Clapper has said he did not oversee any such wiretapping.

The Senate subcommittee is conducting one of several federal investigations into Russia's election tampering. Some of those investigations are also exploring whether the Trump campaign colluded with Russia on those efforts. Besides the Senate Judiciary Committee, the Senate Select Committee on Intelligence, the House Intelligence Committee and the FBI are conducting investigations.

Yates will likely testify before congressional investigators again: Following the cancelation of her previous House Intelligence Committee hearing (and the recusal of that committee's chairman, Representative Devin Nunes), the committee has said it is speaking with her lawyers about scheduling. That committee also invited Clapper and former CIA Director John Brennan to testify.

Monday's hearing will be at 2:30 p.m. EDT and will stream live on C-SPAN and other networks.

This article has been updated to include CNN and NBC News reports about President Barack Obama's​ warning Donald Trump not to hire Michael Flynn.